Middle mouse button pan reactor

[p_mcknight]

I have constructed a reactor to log some data for me during my AutoCAD editing sessions.  I would like to add a call to my function based off of a middle mouse button click or a middle mouse button pan.  As the middle mouse button pan does not register as a command I cannot use a command reactor.  I looked at a system variable reactor (to see if by chance the viewctr or etc would register as changed, they do not).  I cannot seem to come up with any way to know when this event has taken place.  I would like to do this all in LISP but if there is no way then I suppose I can branch out and add some code to my custom .net class library.  I would prefer to not have to do this.  Does anyone have any ideas?